One aspect of plasma membrane structure which has gained much attention over the last three years is the mobility of both the lipid and protein components in the lateral plane of the surface membrane. The use of plant agglutinins (lectins) has permitted a phenomenologically directed analysis of the mechanism whereby the relative degree of mobility of specific surface glycopeptides is controlled. We propose to use the data outlined in two enclosed manuscripts as a base from which to examine the mechanism whereby a particular series of Chinese hamster ovary sub-clones regulate the lateral mobility of their lectin receptor sites. These CHO sub-clones are well suited for this study in that they respond rapidly in terms of both their morphology and surface architecture to growth in media containing dibutyryl cyclic AMP. Specifically we intend to test a model which suggests that lectin receptor mobility in these CHO sub-clones is dependent on the degree of association of the lectin receptors with a stationary peptide complex, which in turn is held in a fixed mode via its association with intracellular micro tubules and microfilamants. We present evidence in this proposal suggestive of a role for membrane peptide phosphorylation in controlling lectin receptor mobility and emphasize the use of lectin affinity chromatography for isolating and characterizing surface receptor complexes. Finally, we propose to use scanning electron microscopy on the four individual CHO sub-clones to analyze the role of microvilli in controlling lectin-initiated cell agglutination.